The key
A spring-loaded switch. Pressing it closes a circuit and lets current flow.
A key · a wire · a message
Morse Code Telegraph
Press the key. Hear the sounder. Read what you sent.
An electric telegraph sends timed electrical pulses along a wire, and a sounder turns them into audible clicks at the receiving end. Samuel Morse and Alfred Vail developed the system used on the 1844 Washington–Baltimore line; Morse sent the first public message, “What hath God wrought,” on May 24 of that year. This tool simulates a key and sounder in your browser.
Your speed12 WPMDot length100 ms
Timing guide and fixed speed
International: dot 1 unit, dash 3; leave 3 units between letters and 7 between words. American: internal gaps 2 units, L dash 4 units, 0 dash 5 units. Use fixed speed when practising long dashes.
On the paper tape
Your message appears here
Press the key to begin.
Practice drill
WaitingNothing you tap leaves this page.
American vs International Morse
Eleven letters and nine digits differ. All ten digits are shown below; 4 is shared. A space inside an American pattern is a pause within that letter, not a new letter.
| Character | International | American | What changed |
|---|---|---|---|
| C | -.-. | .. . | A gap inside the letter |
| F | ..-. | .-. | Different pattern |
| J | .--- | -.-. | Different pattern |
| L | .-.. | ⸺ | Long dash: 4 units |
| O | --- | . . | A gap inside the letter |
| P | .--. | ..... | Different pattern |
| Q | --.- | ..-. | Different pattern |
| R | .-. | . .. | A gap inside the letter |
| X | -..- | .-.. | Different pattern |
| Y | -.-- | .. .. | A gap inside the letter |
| Z | --.. | ... . | A gap inside the letter |
| 0 | ----- | ⸻ | Long dash: 5 units |
| 1 | .---- | .--. | Different pattern |
| 2 | ..--- | ..-.. | Different pattern |
| 3 | ...-- | ...-. | Different pattern |
| 4 | ....- | ....- | Same in both codes |
| 5 | ..... | --- | Different pattern |
| 6 | -.... | ...... | Different pattern |
| 7 | --... | --.. | Different pattern |
| 8 | ---.. | -.... | Different pattern |
| 9 | ----. | -..- | Different pattern |
How a telegraph actually worked
The line
A wire carries the current between stations. Many landlines used the earth as the return path.
The sounder
An electromagnet pulls an arm down with a click. A second click follows when the current stops.
The operator
A trained operator listened to the timing and wrote the message in ordinary words.
A sounder is not a buzzer. Listen for the interval between the down-click and the up-click: short for a dot, longer for a dash. This tool synthesizes those two clicks.
A brief telegraph history
Morse sent “What hath God wrought” from Washington to Vail in Baltimore on May 24, 1844. Vail sent a reply to confirm that the message arrived. The Smithsonian describes the original message and the Washington–Baltimore line.
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Questions people ask
What is American Morse?
It is the older landline code used by American telegraph operators. Some characters contain an extra gap, and L and 0 use long dashes. International Morse is the alphabet used by the other tools here.
Why does a sounder click twice?
Closing the key pulls the sounder arm down; releasing it lets the arm return. Operators read the time between the two clicks and the gaps between signals, rather than a continuous musical tone.
Can I connect a real telegraph key?
A keyboard interface that sends Space can operate the focused key. Compatibility depends on your adapter. This browser tool does not connect directly to electrical telegraph circuits.
Can two people use it together?
This key runs locally on one device. The Simulator shows two stations and a message travelling between them; it is not an online chat connection.
American patterns: 1912 Wireless Course chart, Electro-Importing Company, pp. 113–114. Key mechanism: Smithsonian telegraph key collection.
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